You signed up for a new fitness program because the workouts were only 30 minutes and the sessions were short enough to fit into your busy schedule. You gave them your credit card and began working out. You’ve been at it for a while but you aren’t seeing the results you wanted. You aren’t alone, especially if losing body fat is one of your goals.
Why do 30 minute workouts not help participants achieve the desired results as well as 45 minutes? First, science has proven that once we enter a moderate level of intensity in our workout, our bodies initially burn carbohydrate stores to provide the fuel for the work we’re doing. According to Dr. Michael G. Kurilla, of the National Institute of Allergy and Infectious Diseases, at some point we switch to fat for fuel, and when that switch occurs depends on your fitness level. Elite level athletes and very fit people tap into fat stores sooner, but on average most of us can expect to make the switch from carbs to fat at around 15 to 20 minutes into moderate-intensity aerobic exercise. Another expert, Damian Verial, who holds a Master of Science degree, recently published an article estimating 30 minutes for the carb burning period. Either way, after that initial period, carb stores become depleted and only then do our bodies begin to burn fat as the primary source for required energy. This means if you are in a 30 minute workout with a 5 minute warmup and a 5 minute cool down, you may only be in the maximum fat burning zone for a minute or so. You are burning very little body fat.
Compare this to a 45 minute workout that adds the cool down after the workout, as opposed to taking it from the higher intensity time. You would spend at least 20 minutes longer in the desired zone, and burn 15 minutes more calories at your peal level. For example, Let’s say you burn 10 calories a minute during your warm up and cool down, but 18 per minute in the higher intensity portion. That would mean a 30 minute workout would burn 460 calories, but a 45 minute workout plus cool down would burn 730 calories. Those 270 extra calories per workout could mean an additional 16 plus pounds of fat lost per year, based on four workouts per week. How would an additional 16 pounds lost sound to you?
Longer sessions impact more than just fat loss. In a 2015 study published in the journal, Circulation, it was shown that while 30 minutes of daily exercise had a “modest” reduction in risk for heart failure, that lowering of risk went up drastically when the exercise time was increased.
Jim Harris, the author, is a Master Trainer, holding multiple advanced certifications, including Nutrition and Weight Loss. He contributes to several publications, and is the Founder/Owner of Max Results Training LLC, pulse 45 Fitness and the owner of Oakwood BodyPlex and Harris Fitness Consulting LLC, along with his wife, Marian, who recently published her second book, Inhale, Exhale: Everyone Has A Story”